(1) Field of the Invention
This invention relates to the heat transfer printing of fabrics with disperse dyes. More specifically it relates to the screen printing or spraying of cellulose-containing textile materials with a crosslinking system to improve the affinity of such textiles for disperse dyestuffs.
(2) Description of the Prior Art
Heat transfer printing is a process whereby a paper containing disperse dyestuffs on the surface is placed in contact with a suitable material and heated, so that the sublimable dyes are transferred from paper to fabric. Unmodified cellulose cannot be effectively heat transfer printed with disperse dyes because of a lack of affinity. Very little dye is adsorbed by the cellulose, and this small amount is removed upon washing. This is in marked contrast to the effect obtained with some synthetic textiles, such as polyester, which have excellent affinity for disperse dyes.
Lambert, British Pat. No. 1,445,201, has demonstrated that the affinity of a cellulose-containing textile for disperse dyes can be improved by treatment with a methylated melamine-formaldehyde resin in which there are five-CH.sub.2 OCH.sub.3 groups per melamine group. The fabric is printed by heating for 3 minutes at 200.degree.-210.degree. C. with transfer paper containing disperse dyes. This longer printing time is needed because of the use of a weaker catalyst, such as (NH.sub.4)H.sub.2 PO.sub.4, than is usually used for resin finishing of cellulose.
British Pat. No. 1,460,742 teaches that cellulose-containing fabrics can be effectively transfer printed with disperse dyestuffs if the fabric is impregnated with at least one curable resin containing one or more hydroxymethyl, alkoxymethyl or aldehyde groups that are capable of reacting with the disperse dyestuffs.
Faulhaber et al, U.S. Pat. No. 4,063,879, teaches that the fabric has to be impregnated with the aminoplast and then transfer printed by sublimation from a paper containing a disperse dyestuff and volatile acid, or metal or ammonium salt of the volatile acid.
Vellins et al, U.S. Pat. No. 4,072,462 specifies the use of disperse dyes with reactive groups which can react with the aminoplast during the printing process to obtain colorfastness to washing. Vellins teaches that free acids are not generally used as catalysts because they adversely affect bath stability.
Transfer printing on garments is described in British Pat. No. 1,243,223 in which case a garment of wool fibers is contacted with an aluminum plate containing a basic dye.